The invention relates to an effect imparting device used in an electronic musical instrumental or the like apparatus and, more particularly, to an effect imparting device of a type imparting a desired effect by delaying a tone signal capable of eliminating or preventing a click noise produced in changing length of delay.
In effect imparting devices used in electronic musical instruments or the like apparatus, there are devices imparting modulation effects such as "delay", "reverberation", "phase shifting", "vibrato" and "termolo" by employing a digital delay device (e.g., Japanese Preliminary Patent Publication Nos. 58-14191 corresponding to U.S. Ser. No. 07/161,344 and 58-14898 corresponding to U.S. Ser. No. 07/022,582, U.S. Pat. No. 4,472,993 and U.S. Pat. No. 4,569,268).
Delay length in a digital delay device sometimes is automatically changed during processing of a tone signal by operation by a player or in accordance with a processing program. In that case, there arises the inconvenience that the phase of a delay output signal after the change becomes discontinuous to that before the change resulting in generation of a click noise in a signal portion at the change. Particularly, in an effect, e.g., an reverberation effect, in which a delay output signal is fed back to the input side of the delay device, the click noise thus generated also is fed back, and this poses a serious problem.